NAME

       zmq_msg_send - send a message part on a socket

SYNOPSIS

       int zmq_msg_send (zmq_msg_t *msg, void *socket, int flags);

DESCRIPTION

       The zmq_msg_send() function is identical to zmq_sendmsg(3), which shall be deprecated in
       future versions. zmq_msg_send() is more consistent with other message manipulation
       functions.

       The zmq_msg_send() function shall queue the message referenced by the msg argument to be
       sent to the socket referenced by the socket argument. The flags argument is a combination
       of the flags defined below:

       ZMQ_DONTWAIT
           For socket types (DEALER, PUSH) that block (either with ZMQ_IMMEDIATE option set and
           no peer available, or all peers having full high-water mark), specifies that the
           operation should be performed in non-blocking mode. If the message cannot be queued on
           the socket, the zmq_msg_send() function shall fail with errno set to EAGAIN.

       ZMQ_SNDMORE
           Specifies that the message being sent is a multi-part message, and that further
           message parts are to follow. Refer to the section regarding multi-part messages below
           for a detailed description.

       The zmq_msg_t structure passed to zmq_msg_send() is nullified on a successful call. If you
       want to send the same message to multiple sockets you have to copy it (e.g. using
       zmq_msg_copy()). If the call fails, the zmq_msg_t structure stays intact, and must be
       consumed by another call to zmq_msg_send() on the same or another socket, or released
       using zmq_msg_close() to avoid a memory leak.

           Note
           A successful invocation of zmq_msg_send() does not indicate that the message has been
           transmitted to the network, only that it has been queued on the socket and 0MQ has
           assumed responsibility for the message. You do not need to call zmq_msg_close() after
           a successful zmq_msg_send().

   Multi-part messages
       A 0MQ message is composed of 1 or more message parts. Each message part is an independent
       zmq_msg_t in its own right. 0MQ ensures atomic delivery of messages: peers shall receive
       either all message parts of a message or none at all. The total number of message parts is
       unlimited except by available memory.

       An application that sends multi-part messages must use the ZMQ_SNDMORE flag when sending
       each message part except the final one.

RETURN VALUE

       The zmq_msg_send() function shall return number of bytes in the message if successful (if
       number of bytes is higher than MAX_INT, the function will return MAX_INT). Otherwise it
       shall return -1 and set errno to one of the values defined below.

ERRORS

       EAGAIN
           Non-blocking mode was requested and the message cannot be sent at the moment.

       ENOTSUP
           The zmq_msg_send() operation is not supported by this socket type.

       EINVAL
           The sender tried to send multipart data, which the socket type does not allow.

       EFSM
           The zmq_msg_send() operation cannot be performed on this socket at the moment due to
           the socket not being in the appropriate state. This error may occur with socket types
           that switch between several states, such as ZMQ_REP. See the messaging patterns
           section of zmq_socket(3) for more information.

       ETERM
           The 0MQ context associated with the specified socket was terminated.

       ENOTSOCK
           The provided socket was invalid.

       EINTR
           The operation was interrupted by delivery of a signal before the message was sent.

       EFAULT
           Invalid message.

       EHOSTUNREACH
           The message cannot be routed.

EXAMPLE

       Filling in a message and sending it to a socket.

           /* Create a new message, allocating 6 bytes for message content */
           zmq_msg_t msg;
           int rc = zmq_msg_init_size (&msg, 6);
           assert (rc == 0);
           /* Fill in message content with 'AAAAAA' */
           memset (zmq_msg_data (&msg), 'A', 6);
           /* Send the message to the socket */
           rc = zmq_msg_send (&msg, socket, 0);
           assert (rc == 6);

       Sending a multi-part message.

           /* Send a multi-part message consisting of three parts to socket */
           rc = zmq_msg_send (&part1, socket, ZMQ_SNDMORE);
           rc = zmq_msg_send (&part2, socket, ZMQ_SNDMORE);
           /* Final part; no more parts to follow */
           rc = zmq_msg_send (&part3, socket, 0);

SEE ALSO

       zmq_recv(3) zmq_send(3) zmq_msg_recv(3) zmq_socket(7) zmq(7)

AUTHORS

       This page was written by the 0MQ community. To make a change please read the 0MQ
       Contribution Policy at http://www.zeromq.org/docs:contributing.